Automatic ice removal



May 23, 1939. Ki s. TYLER AUTOMATIC ICE REMOVAL Filed Aprilv 26, 1938 INVENTOR.

Patented May 23, 1939 AUTOMATIC ICE BIMOYAL Kingdon S. Tyler, Bloomfield, N. J., assignor to Eclipse Aviation Corporation, East Orange,- N. J., a corporation of New Jersey Application April 26, 1938, Serial No. 204,474

50Min.

This invention relates to aircraft. and more particularly to a means for preventing the accumulation of ice on aircraft surfaces, such as the wing and tail structures, the propeller blades, land other exposed surfaces.

It is well known that under certain conditions of temperature and relative humidity, ice will form on the structural parts of an airplane. This formation is cumulative and at times seriously interferes with the control and operation of aircraft. Themore common locations for the ice formation are the leading edges of the wings and' tail structure.

In Patent No. 1,998,809 granted to G. C. Geer on April 23, 1935 there is illustrated a type of flexible and expansible overshoe provided upon such leading edges of the wings4 and tail structures and adapted to expand and contract periodically-in response to the operation of pneumatic energizing means.

An object of the, present invention is to provide for the automatic control of the operation of such overshoes", or other suitable type of ice removingmeans, so as to relievethe operator of the craft of the necessity of maintaining vigilance to determine the proper moment for bringing such mechanism into operation.

Other objects of the invention will become apparent upon examination of the following description which is to be read in connection with the accompanying drawing illustrating two embodiments of the invention.

Fig. 1 is a view in transverse section of an aerofoil structure and associated parts embodying the invention;v

Fig. l2 is a diagram of the electrical connections for the system of Fig. 1; and

Fig. 3 shows a second embodiment.

Referring to the drawing, reference character 5 designates anelectric device for controlling the energization of the overshoe actuating means, or any equivalentice dislodging mechanisxn,A and reference character 6 indicates a source of current for supplying the unit 5 with the operating energy required.

Reference character 2i designates a switch adapted to be operated by a linkage 8, 9, Athe linkage being normally held in vopen' circuit position by suitable means such as the coiled compression spring il located in a recess in the wall i2 forming a part of, or an extension of, the aerofoil section I3 which in turn may be an integral part of the wing surface of the craft or other" aerofdii surface from which it is intended to remove ice, or the said elements i2 and i3 may be mounted in proximity to the surface from which ice is to be removed, in which case element I3 will preferably include ice removing means of its own which may take the form of 5 an electrical resistance unit I4 adapted to generate sufllcient heat for the purpose upon the flow-of current therethrough, the circuit to the said heating coil' I4 being indicated in Fig; 2.

At the end of the rod or link 8 opposite to that which is acted upon by the spring Ii, there is vprovided a formation i8 adapted to move outcase of a structure as indicated in Fig. 1 would result in an increase in the over-al1 lengthof the assembly, beginning at the fixed point I8,

so that such increased length will produce a cor- 5 responding shifting of the rod 9 to the left as viewed in Fig. 2 and hence a swinging of the link or lever 0 in a counter-clockwise direction about its fulcrum i9. This counter-clockwise swinging of the lever 8 will produce a closure of the switch mounted in the housing 2 i, by reason of the connection 22 between the lever 8 and the switch actuating rod 23. Closure of the switch 2l reults in a flow of current to the ice removing control unit 5, the circuit being from the source i by way of conductors 26 and 21, switch 2|, and

conductors 28, 28 and 30; the current returning to the source by way of the ground connection 3i. There is preferably an index element l2 located in the branch 33 of the circuity just traced, so that the operator will have knowledge of the proper functioning of the system. There is also a second branch 34 leading to an electromagnetic kdevice 25 which, upon energization, creates a force tending to bridge the switch contacts 36 45 and 31 and thus supply cu'rrent to the heater coil il heretofore described, and constituting the ice removing or de-frosting means for the control unit i3. In order to allow a predetermined time delay between the beginning of operation of the ice removing control motor 5 and thel actual energization of the de-frosting unit il, there is provided a means for retarding the switch closing action of the electromagneticu n plunger 38. This retarding means may take any desired form, but is shown as embodied in a dashpot cylinder and piston, 39 and 4U respectively, the retarding effect of which may be controlled by varying the size of the suction controlling oriilce 4I.

In the embodiment shown in Fig. 3 the time delay relay of Figs'. 1 and 2 is replaced by a pair ofcooperating switch elements 5I and 52 which are adapted to close upon a predetermined amount of movement of the switch element 2Ia corresponding to the switch 2| of the first embodiment.- As shown, the expansionof the assembly I3 which is produced by the formation of ice thereon causes a movement of the'switch element Zlatoward the cooperating switch element '2lb which, as shown, is integral with the' switch contacts 5| just described. When the expansion is suilicient, a circuit will be closed to the ice removing control unit 5 and the indicator 32, the circuit passing from source 6 by way of conductors 53 and 5I, switch elements 2Ia and 2lb, and conductor 55. Upon a further predetermined amo'unt of movement of the switch elements 2Ia and 2lb in unison, under the continuing expansion of the assembly I 3', a second circuit will be closed lto energize the de-frosting coils H', this second circuit passing from the source S'by way of conductor 56,- switch elements 52 and 5I (normally held apart by resilient means indicated at 51) and thence to the coils Il by way of conductor 58. When sufilcient ice has been-removed the resulting contraction of the assembly I3' under the pressure exerted by the compression spring 59 (corresponding tothe spring Il of Fig. 1) will cause a return of the parts to the position indicated in Fig. 3.and a resulting'cessaticn of operation of the ice removing control motor 5. '-Should the craft be still in. a region of ice formation, the cycle of events above described will be repeated as often as is necessary to prevent undue accumulation of ice.

Where manual operation of the ice removing means is considered sufllcient, the connections to the automatic unit 5 will of course be eliminated, but the mechanism will still function to give an indication, through signal 32, whenever ice begins to' form, and the de-frosting circuit may likewise continue to function, if desired.

1. 'Ihe combination, with an. aerofoil surface and an auxiliary unit associated therewith, of means for removing ice therefrom, means operated by ice formed on said auxiliary unit to control energization of said ice removing means, means 'for de-frosting said auxiliary unit, and

means for operating said de-frosting means in pre-determined time relation to the operation of said ice removing means.

2. The combination, with an aerofoil surface and an auxiliary unit associated therewith, of means for removing ice therefrom, means operated by ice formed on said auxiliary unit to conmeans for removing ice therefrom, means operated by ice formed on said auxiliary unit to control energization of said removing means, said last-named means including a circuit controlling switch, means shiftable by the expansion of the freezing ice to operate said switch, means for de-frosting said auxiliary unit, means for operating said de-frosting means in predetermined time relation to the operation of said switch, said last-named means including a second switch closeable upon lfurther movement of said rstnamed switch.

4. The combination, with an aerofoil surface and an auxiliary unit associated therewith, of means for removing ice therefrom, means operated by ice formed on said auxiliary unit to control energ'ization of said removing means, said last-named means including a circuit controlling switch, means shiftable by the expansion of the freezing ice to operate said switch, means for de-frosting said auxiliary unit, means for operating said 'de-frosting means in predetermined time relation to the operation of said4 switch,

said last-named means including a second switch closeable in response to the passage of current through Ythe circuit. controlled by said firstnamed switch.

5. 4'I'he combination, with an aerofoil surface andan auxiliary unit associated therewitlnof means for removing ice therefrom, means operated by ice formed on said auxiliary unit to indicate the formation of such ice, said last-named means including 'a circuit controlling switch, means shiftable by the expansion of thefreezing ice to operate said switch, means for defrostng said auxiliary unit, and means for operating said de-frosting means in predetermined -time relation to the operation of said switch.

KING-DON S. TYLER. 

